Apparatus and method for in-situ electromagnetic extraction and production of hydrocarbons from geological formations

ABSTRACT

Presented is a system for extracting subsurface oil using microwave or RF energy generated above the ground surface, and directed to an underground oil bearing location using a coaxial transmission line functioning as a wave guide.

PRIORITY/CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the priority date of the provisional applicationentitled APPARATUS AND METHOD FOR IN-SITU ELECTROMAGNETIC EXTRACTION ANDPRODUCTION FO HYDROCARBONS FROM GEOLOGICAL FORMATIONS filed by George M.Harris on Apr. 3, 2008, with application Ser. No. 61/042,150, thedisclosure of which is incorporated by reference.

FIELD OF THE INVENTION

The invention generally relates to an apparatus for underground oilrecovery, and more particularly to a microwave assisted system of oilrecovery.

BACKGROUND OF THE INVENTION

There are huge quantities of oil which would be available for use if theoil could be extracted from the substrate with which it is combined.This includes oil bearing substrates such as oil shale, tar sands, andother similar hydrocarbon bearing geological formations.

Many strategies have been put forward for extracting oil from suchgeologic formations. One strategy is to drill a number of shafts in sucha geologic formation, and use explosives to fracture and pulverize alarge quantity of material, which by heat and pressure would then causethe oil to separate from the geologic substrate, and be pumpable out ofthe underground region that is the site of the explosion.

Other methods have involved mining the substrate, such as by pit miningor strip mining and then processing the material through a heat processwhich would free the oil from the substrate.

All of these strategies have their problems, and what is needed is anapparatus and method which does not require excavation of hugequantities of underground material, nor which utilizes dangerousunderground explosions.

SUMMARY OF THE INVENTION

The invention embodies both an apparatus and a method for the productionof hydrocarbons using high power microwave or radio frequency, (RF)energy, in-situ, within hydrocarbon-bearing geological formations. Theinvention converges two major technologies; one is the efficientapplication of electromagnetic energy, (microwaves or RF), and the otherinvolves gathering the hydrocarbon that is produced in-situ,electromagnetically and then transporting it to the surface where it iscollected. This invention can be used to produce and recover hydrocarbonproducts from geological components such as oil shale, tar sands andother similar hydrocarbon-bearing geological formations.

The invention uses microwaves that are applied in-situ, (actually withinthe formation, usually in the ground), to produce hydrocarbon productsfrom hydrocarbon products from hydrocarbon-bearing material such asfine-grained sedimentary rock that makes up oil shale or othercomponents of a geological formation where hydrocarbon material issought.

The invention is implemented using a combination of five major elements:

1. A high power microwave applicator that launches electromagneticenergy directly into a geological formation in-situ.

2. A mechanical pumping mechanism located just below the high powerelectromagnetic applicator.

3. A system of mechanical couplings and actuators that transport themechanical pumping power from the pump actuator motor to the pumpsection of the invention itself.

4. A system of electromagnetic energy transmission system such coaxialline or waveguide that transports the energy from a transmitter to theapplicator where it is applied, in-situ to the geological formation forhydrocarbon product production.

5. A high power electromagnetic energy transmission system such coaxialline or waveguide that transports the energy from a transmitter to theapplicator where it is applied, in-situ to the geological formation forhydrocarbon product production.

The entire assembly is usually placed in a hole or well, usuallydrilled, bored, or dug into a geological formation containing thehydrocarbon-bearing material. High power microwaves or radio frequency,(RF), energy from a transmitter or high power microwave or RF generatoris transmitted through the coaxial transmission line or waveguide systemto the applicator portion of the invention. The applicator launches theenergy directly into the formation where it interacts volumetricallywith the hydrocarbon compounds in the formation, liberating thehydrocarbons as well as reducing the components' viscosity, therebymaking it easier for the hydrocarbon material to run freely. Theproduced hydrocarbon product then flows by gravity into the shaftoccupied by the invention, and migrates toward the lower portion of theapparatus where it is extracted. There, a pump on the lower end of theinvention extracts the hydrocarbon material and pumps it to the surfacewhere it is recovered.

In the present embodiment of the invention, the electromagnetic energyused in the extraction and/or pre-processing of the hydrocarbon is keptseparate from the hydrocarbon once it is produced from the geologicalformation and drawn into the pump portion of the apparatus using asystem of electromagnetic choke structures. These choke structures allowconnection of pipes carrying the liquid hydrocarbon to the collector,usually located at the surface, to the high power microwave or RFtransmission line system responsible for transmitting the high powermicrowave or RF energy to the applicator. The apparatus is also designedso that the mechanical components that transmit mechanical power to thepump are kept separate from the high power electromagnetic energy usedto produce the hydrocarbon product.

The purpose of the Abstract is to enable the public, and especially thescientists, engineers, and practitioners in the art who are not familiarwith patent or legal terms or phraseology, to determine quickly from acursory inspection, the nature and essence of the technical disclosureof the application. The Abstract is neither intended to define theinvention of the application, which is measured by the claims, nor is itintended to be limiting as to the scope of the invention in any way.

Still other features and advantages of the claimed invention will becomereadily apparent to those skilled in this art from the followingdetailed description describing preferred embodiments of the invention,simply by way of illustration of the best mode contemplated by carryingout my invention. As will be realized, the invention is capable ofmodification in various obvious respects all without departing from theinvention. Accordingly, the drawings and description of the preferredembodiments are to be regarded as illustrative in nature, and not asrestrictive in nature.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross sectional view of the apparatus of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the invention is susceptible of various modifications andalternative constructions, certain illustrated embodiments thereof havebeen shown in the drawings and will be described below in detail. Itshould be understood, however, that there is no intention to limit theinvention to the specific form disclosed, but, on the contrary, theinvention is to cover all modifications, alternative constructions, andequivalents falling within the spirit and scope of the invention asdefined in the claims.

In the following description and in the FIGURES, like elements areidentified with like reference numerals. The use of “e.g.,” “etc.,” or“or,” indicates non-exclusive alternatives without limitation unlessotherwise noted. The use of, “including” means, “including, but notlimited to,” unless otherwise noted.

FIG. 1 shows a cross-sectional view of a preferred embodiment of theinvention. Shown in a hydrocarbon bearing substrate 46 which has asurface 48 on the surface 48 is located a microwave source 12. Themicrowave source 12 can take a number of configurations but oneembodiment which is considered to be preferable is a 125 kilowattmicrowave source. Depending on the installation, this could operate at915 MHz or 460 MHz. Other frequencies are also possible depending on thedesign of the particular installation.

Attached to the microwave source 12 is an interview inlet section 14.This includes an inlet inner conductor 16, and is the connection betweenthe microwave energy source and a coaxial transmission line 44. Thecoaxial transmission line 44 includes a first choke section 26. Thefirst choke section 26 is a short section of coaxial transmission line44, which is one quarter wave length in length. This particularconfiguration causes microwave energy which enters the energy inletsection 14 to be blocked from entering the first choke section 26, andthus all of the microwave energy is directed downward to the coaxialtransmission line 44. This choke is short circuited with the outerconductor in the same manner as the second choke is short circuited. Thecoaxial transmission line 44 functions in the role of the wave guide foreither microwave or radio frequency (RF) energy. These energies areconsidered equivalent in the context of this application, and energygreater than 300 MHz, by convention are all considered to be a form ofmicrowave energy.

The down tube outer conductor 18 and the down tube inner conductor 20,act as a wave guide and do, in a microwave context, direct energy alongthe path without absorbing energy. In this case, the microwave or RFenergy is directed towards the bottom end of the down tube outerconductor 18. The down tube outer conductor 18 is placed in a bore hole22 which has been drilled into the hydrocarbon substrate 46. As themicrowave energy travels down the coaxial transmission line 44 itencounters a number of radiating centers 36. The radiating structures orradiating centers 36 are provided to allow energy, extracted from thecoaxial transmission line 44 to exit the coaxial transmission line 44.The energy thus released from the coaxial transmission line 44 heats thehydrocarbon bearing substrate 46 which is adjacent to the bore hole 22.The substrate which is heated releases the oil which is absorbed orbonded to the substrate. In this way the oil is mobilized, and a regionof productive, heated substrate expands radially away from the innerdiameter of the bore hole wall, starting from the bore hole.

An oil production front expands into the adjacent substrate 46, and asoil is released from the substrate, the substrate becomessemi-transparent to the microwave or the RF energy. As oil is producedit flows into the bottom of the bore hole 22, where it is in contactwith the pump out port 32 of the down tube inner conductor 20.

The down tube inner conductor is also a steel pipe, with its outersurface interacting with the inner surface of the down tube outerconductor 18 to act as a wave guide for energy between the two surfaces.Inside the down tube inner conductor is a reciprocating pump rod. Thereciprocating pump rod 28 extends out the end of the first chokesection, and passes through a sliding seal 40. The reciprocating motionis imparted to the reciprocating pump rod 28 by a reciprocating motiveforce above the surface of the ground. This causes the reciprocatingpump rod 28 to move up and down in a reciprocating motion. In a downhole pump section a down hole pump is located. It is the down hole pumpwhich raises oil above the surface of the ground. The oil cannot bewithdrawn by vacuum, because that would only lift it a short distance.Therefore the oil 34 is lifted by pushing the oil 34 with a down holepump 30 in the down hole pump section. This pump operates in a mannersimilar to other oil pumping operations which are driven by areciprocating rod from the surface of the ground. Oil is lifted insidethe down tube inner conductor 20, and surrounds the reciprocating pumprod 28. As it fills the interior of the down tube inner conductor 20, iteventually reaches a point above the surface where there is located asecond choke section 24. The second choke section 24 is the oil outputsection. This section includes an outer tube and an inner tube, with theinner tube extending out from a short-circuiting closure plate and oilbeing routed through the inner conductor of the second choke section.The second choke section is also one quarter of one wavelength inlength, and therefore forms a choke to the microwave energy. Thus, nomicrowave energy travels into the second choke section 24.

The exemplary embodiments shown in the FIGURES and described aboveillustrate but do not limit the invention. It should be understood thatthere is no intention to limit the invention to the specific formdisclosed; rather, the invention is to cover all modifications,alternative constructions, and equivalents falling within the spirit andscope of the invention as defined in the claims. For example, while theexemplary embodiments illustrate a microwave source, the invention isnot limited to use with a microwave source and may be used with otherenergy sources such as RF energy sources. While the invention is notlimited to use with microwaves, it is expected that various embodimentsof the invention will be particularly useful with this type of energy.Hence, the foregoing description should not be construed to limit thescope of the invention, which is defined in the following claims.

While there is shown and described the present preferred embodiment ofthe invention, it is to be distinctly understood that this invention isnot limited thereto but may be variously embodied to practice within thescope of the following claims. From the foregoing description, it willbe apparent that various changes may be made without departing from thespirit and scope of the invention as defined by the following claims.

1. An oil extraction system using application of surface generatedenergy and subsurface energy application, and a surface reciprocatingforce, for energy assisted oil extraction for extracting oil from aborehole comprising: a surface mounted energy source for producingenergy for routing to at least one subsurface oil collection point insaid borehole; a subsurface energy applicator configured to be loweredinto said borehole, for launching surface generated energy into adjacentoil bearing substrate, and operatively connected to said surface mountedenergy source; an energy transmission system operatively connected tosaid energy source and to said subsurface energy applicator, andcomprising a coaxial transmission line, and at least one energy chokeconfigured for blocking said transferred energy from exiting saidtransmission system; and a downhole oil pumping system comprisingmechanical couplings and actuators configured to transport oil from saidsubsurface oil collection points in said drill shaft to a surfacecollection point.
 2. The oil extraction system of claim 1, in which saidsurface mounted energy source is a microwave energy generator.
 3. Theoil extraction system of claim 1, in which said surface mounted energysource is a radio frequency energy generator.
 4. The oil extractionsystem of claim 1 in which said coaxial transmission line is a waveguide formed between an inside surface of an outer tubular conductor andan outside surface of an inner tubular conductor.
 5. The oil extractionsystem of claim 1 in which said energy choke is a section of outertubular conductor of a length equal to 0.25 wavelengths of the energybeing transmitted.
 6. The oil extraction system of claim 5 which furthercomprises a first energy choke parallel and contiguous with said outertubular conductor.
 7. The oil extraction system of claim 5 in which saidfirst energy choke further comprises a seal for said inner tubularconductor and is configured to allow said inner tubular conductor toextend beyond an end of said first energy choke.
 8. The oil extractionsystem of claim 5 which further comprises a second energy choke normaland contiguous with said outer tubular conductor, and positioned abovesaid ground surface.
 9. The oil extraction system of claim 5 in whichsaid second energy choke further comprises a seal for a section of saidinner tubular conductor and is configured to allow said inner tubularconductor to extend beyond an end of said second energy choke, with saidsecond energy choke comprising an oil output port.
 10. The oilextraction system of claim 4 in which said downhole oil pumping systemfurther comprises a reciprocating pump rod enclosed within said innertubular conductor, with said reciprocating pump rod operativelyconnected to a downhole pump, and a reciprocating force above saidground surface.
 11. An oil extraction system using surface generatedenergy and subsurface energy application, and a surface reciprocatingforce, for energy assisted oil extraction for extracting oil from aborehole comprising: a surface mounted energy source for producingmicrowave energy for routing to at least one subsurface oil collectionpoints in said borehole: a subsurface energy applicator configured to belowered into said borehole, for launching surface generated energy intoadjacent oil bearing substrate, and operatively connected to saidsurface mounted microwave energy source; an energy transmission systemoperatively connected to said energy source and to said subsurfaceenergy applicator, and comprising a coaxial transmission line with anouter tubular conductor, and an inner tubular conductor, with an insidesurface of said outer tubular conductor and an outside surface of saidinner tubular conductor forming a wave guide for conducting microwaveenergy; a first energy choke parallel and contiguous with said outertubular conductor and configured for blocking said transferred energyfrom exiting said energy transmission system and comprising a section ofouter tubular conductor of a length equal to 0.25 wavelengths of theenergy being transmitted, with said first energy choke comprising a sealfor said inner tubular conductor configured to allow said inner tubularconductor to extend beyond an end of said first energy choke; a secondenergy choke normal and contiguous with said outer tubular conductor,positioned above said ground surface, comprising a seal for a section ofsaid inner tubular conductor and is configured to allow said innertubular conductor to extend beyond an end of said second energy choke,with said second energy choke further comprising an oil output port; anda downhole oil pumping system comprising a downhole pump, areciprocating pump rod enclosed within said inner tubular conductor,with said reciprocating pump rod operatively connected to a downholepump, and a reciprocating force above said ground surface, and furthercomprising mechanical couplings and actuators configured to transportoil from said subsurface oil collection pints in said drill shaft to asurface collection point.